MySQL:如果行相等则求和

Question

我想打一个SQL选择查询,选择一切,但是当client,thickness并且material是应补充同他们的"量"的价值.

我该如何创建这样的查询？

Answer 1

如果我理解正确的话.你可以这样做:

SELECT
    client, 
    thickness,
    material,
    SUM(amount) AS TotalAmount
FROM
    Table1
GROUP BY
    client, 
    thickness,
    material